Method of applying resilient felts to the opposite sidewall portions of a slot



C. W. ANDERSEN METHOD OF APPLYING RESILIENT FELTS TO THE OPPOSITE SIDEWALL PORTIONS OF A SLOT Original Filed Feb. 9, 1962 Feb. 21, 1967 3,305,425

I NVENTOR.

United States Patent Ofiice 3 305 425 METHUD @F APPLYllNG RESlLlENT FlElL'lS T :SlHE OPPOSITE SlDEWALlL PORTIONS OF A LOT Clifiord W. Andersen, De Kalb, 111., assignor to The Warlitzer Company, Chicago, llll., a corporation of Uhio Original application Feb. 9, 1962, Ser. No. 172,184, new Patent No. 3,147,171, dated Sept. 1, H64. Divided and this application Aug. 29, 1963, @er. No. 309,537 (Zlaims. (Cl. 156-293) This is a divisional application of my earlier copending parent application, Serial No. 172,184, filed February 9, 1962, now Patent No. 3,147,171, dated September 1, 1964.

This invention relates generally to musical instruments such as pianos and the like, especially to arrangements for pivoting a key lever in such a musical instrument, and more particularly to methods and apparatus for applying a resilient friction material to portions of such a pivot arrangement.

As is well known, the key levers of a piano are mounted for pivotal movement; and the fulcrum for this movement usually consists of an upstanding pin fastened rigidly to the balance rail of the piano and a felt-lined slot fashioned in the key lever to receive the pin. A similar arrangement consisting of a felt-lined slot in the key lever and a rigidly mounted pin is employed at the front end of the key lever to guide the movement thereof. While the balance rail slots open upwardly, the front rail slots open downwardly.

In accordance with conventional practice, large sheets of felt are coated with animal glue and the glue is allowed to dry. Thereafter, the individual felt parts are cut from the sheet and are moistened with steam to soften the glue immediately prior to insertion of the felt parts in the slots of the kep levers. An almost instantaneous attachment of the felt to the sidewall of the slot occurs. However, animal glue is hygroscopic. As the glue film repeatedly absorbs moisture from the air and dries out due to changing atmospheric conditions, it loses its bonding strength whereby to permit dislocation of the felt parts. Appreciable dislocation of the felt parts destroys proper operation of the key lever requiring repair of the piano. Whereas the use of adhesive materials which are not subject to the difficulties of animal glue has been proposed, these latter adhesive materials have been found to set or harden much too slowly for utilization in the customary procedure.

Accordingly, a general object of the present invention is to provide new and improved methods for applying resilient friction material to a sidewall portion of a hole fashioned in a member defining a key lever for a musical instrument.

Other objects and features of the invention pertain to the particular structure, materials, methods and arrangements whereby the above objects are attained.

The invention, both to its structure and mode of operation, will be better understood by reference to the following disclosure and drawing forming a part thereof, Wherein:

FIG. 1 is a schematic, elevational view in partial crosssection showing apparatus for applying resilient friction material to opposite sidewall portions of the slot fashioned in a member defining a key lever for a musical instrument, the apparatus being shown ready to operate;

FIG. 2 is a schematic, elevational view similar to the showing of FIG. 1 but illustrating the apparatus in its condition at the instant of completing application of the resilient friction material;

FIG. 3 is an enlarged, perspective view of one of the container arrangements with strip of friction material dis posed in place;

FIG. 4 is a perspective view of the container arrange- 3,305,425 Patented F eh. 21, 1967 ment of FIG. 3 with the strip of friction material removed;

FIG. 5 is an enlarged perspective view of a re-usable plug element of the type employed in the invention; and

FIG. 6 is an enlarged, fragmentary perspective view of a key lever, the body of the key lever being cut away to reveal details of the slot which has been lined with resilient friction material in accordance with the invention.

Referring now in detail to the drawings, specifically to FIG. 1, a wooden member 10 is shown fashioned as a keyboard defining a number of unseparated key levers for a piano; and in compliance with conventional practice, the member 1 0 is provided with a suitable number of slots 12 which are particularly adapted to receive balance rail pins, not shown. Each of the slots 12 comprises a bore 14 extending transversely of the member 10 to pass a balance rail pin. A slot 12 further includes a generally rectangular aperture 16 counterbored with the bore 14. A shallow recess 18 is desirably fashioned at each of the oposite lateral edges of the counterbored aperture 16, the recesses 18 being selected to possess a depth slightly greater than the thickness of the resilent friction material which is to be used in lining the slots. With the recesses 18 so fashioned, the friction material can be situated on the floor of the recesses below the upper face of the member 10 and long the opposite sidewalls of the aperture 16 as will be described more fully hereinbelow.

In further compliance with conventional practice, the member 10 is provided with a second series of slots, not shown, which are adapted to receive front rail pins for guiding the movement of the key levers that are ultimately separated from the member 10. These slots for the front rail pins are similar to the slots 12 with the exceptions that the front slots open from the opposite face of mem ber 1t) and do not include bores such as the bores 14.

Of the resilient friction materials which are available for use in lining the slots 12, felt has proved to be particularly advantageous; and in accordance with the present invention, narrow strips of an appropriate felt material are coiled in rolls, such as the rolls 20 and 22. Rolls 2% and 22 are mounted on shafts 24 which are journaled to be rotated freely so as to permit easy withdrawal of continuous lengths 26 and 28 of the felt material from the rolls 20 and 22 respectively. The rolls 20 and 22 are situated in opposed relationship as shown in order to supply the lengths 26 and 28 with respective surface portions thereof disposed in confronting relationship.

The lengths 26 and 28 of felt material are received by container arrangements 30 and 32 respectively, the container arrangements being similarly constructed to be mirror images of each other. The container arrangements 3t} and 32 are furthermore intended to be swingable with a jaw action therebetween; and accordingly, each of the container arrangements, as is particularly Well indicated in FIGS. 3 and 4, comprises a body 34 having ears 36 extending outwardly therefrom. The ears 36 are arranged to receive parallel shafts 38 by which the two container arrangements are mounted for the desired relative movement. In addition, means are provided for biasing the container arrangements 30 and 32 in a generally converging relationship; and these latter means include compression springs 46 shown in FIG. 1.

In accordance with an important feature of the invention, the felt linings for the slots 12 are secured to the sidewalls thereof by means of a waterproof adhesive material; and adhesive materials comprising water emulsions of polyvinyl acetate resins and polyvinyl chloride resins have proved particularly useful in this regard. The container arrangements 31} and 32 are employed in coating opposite, distal surface portions of the lengths 26 and 28 with such an adhesive material; and since adhesive materials of the character described are deleteriously affected by exposure to the atmosphere, the container arrangements 30 and 32 are embodied in a closed system for delivering the adhesive material to the surface portions which are to be coated.

With continued reference to FIG. 1 and with particular reference to FIGS. 3 and 4, each of the bodies 34 of the container arrangements is fashioned to define a chamber for receiving the adhesive material, the adhesive material being indicated in FIG. 1 by the numeral 42. In addition, the adhesive material 42 is delivered to the container arrangements 30 and 32 through flexible supply lines 44 which are connected to a primary reservoir for the adhesive material. Advantageously, suitable quantities of the adhesive material 42 are metered and periodically delivered to the container arrangements in accordance with the demand established by the speed of operation of the apparatus.

In order to coat the opposite surface portions of the end regions of lengths 26 and 28 with the adhesive material, the bodies of the container arrangements are fashioned with open side portions 46 as is indicated in FIG. 4; and with reference to FIG. 3, the open side portions 46 will be seen to receive appropriate portions of the lengths of felt material thereover, the portion of felt material received over an open side portion at any particular instant defining one wall of the container arrangement. As will be recognized, the surface portion of the felt material which it is desired to coat is thus disposed in intimate contact with the adhesive material whereby to absorb quantities thereof sufficient to achieve substantially permanent attachment of the felt material to the sidewalls of the slots 12. As is particularly well shown in FIGS. 3 and 4, the bodies of the container arrangements additionally include opposed lips 48 which define grooves 50 for receiving the lateral edges of the lengths of felt material. The grooves 50 position the felt material over the open side portions 4-6.

In accordance with another important feature of the invention, the end portions of the lengths of felt material which have been exposed to the adhesive material are drawn from the container arrangements 30 and 32 into a slot 12. Specifically, a re-usable plug element 52 is urged between the container arrangements by a reciprocating driver 54 having a suitably recessed head for gripping the plug element. As the plug element 52 is urged between the container arrangements 30 and 32, it frictionally contacts the uncoated, confronting surface portions of the lengths of felt material and, in cooperation with the bias established between the container arrangements by springs 40, drags the end portions of the lengths of felt material from the container arrangements 30 and 32 and into a slot 12 as is shown in FIG. 2. After the driver 54 has properly inserted the plug element and the sandwiching felt material into the slot 12, a coaxial head 56 is urged telescopingly to pass over the driver 54. Head 56 is provided with cutter blades 58 at the opposite sides thereof, and the blades 58 pass over the edges of plug element 52 to contact the lengths of felt material, pinching them against the floor of the recesses 18 and severing them at the lines of contact. This severing of the end portions of the lengths of felt material generally between the slot 12 and the container arrangements 30 and 32 is shown in FIG. 2.

After the felt material has been severed generally between the slot 12 and the container arrangements, the head 56 and the driver 54 are retracted, whereupon the springs 40 return the container arrangements to the position shown in FIG. 1. Thereafter, the container arrangements 30 and 32 are raised slightly to pass the head of the plug element 52 which remains in the felt-lined slot. With the container arrangements thus raised, the member is indexed to align another slot in position for application of the felt material.

The plug element 52 is arranged to wedge the adhesively coated surface portions of the felt material against the opposite sidewall portions of the slot. Therefore and with particular reference to FIG. 5, a plug element 52 will be seen arranged with a stem portion 60 which possesses a generally rectangular cross-section and which possesses a transverse dimension sufiiciently great to wedge the felt material against the sidewalls of a slot 12. The stem portion 60 has a curved lower edge 62 for leading the plug into the slot, the portion 60 merging into a head portion 64. The head portion 64 includes a shoulder 66 on opposite lateral sides of the stem portion, and these shoulders confine portions of the lengths of felt material against the floor of the recesses 18. The head portion 64 also includes a T-shaped handle 68 for use in manipulating the plug element.

After the adhesive material has set, bonding the felt elements to the sidewalls of a slot 12, the plug element 52 is withdrawn from the slot as is indicated at the numeral 70 in FIG. 2. It is to be recognized that, after the plug element has been thus withdrawn, it may be used again in drawing felt into a slot and subsequently holding the severed felt elements in place while the adhesive hardens.

It is also to be recognized that the slots for the front rail pins will be lined with felt in a manner similar to that just described relative to the slots for the balance rail pins.

A slot 12 in its completed form and with the plug element removed is shown in greater detail in FIG. 6. There, felt elements 72 and 74 line the opposite sidewall portions of the rectangular aperture 16, being formed outwardly at the upper edges of aperture 16 to line portions of the floor of the recesses 18. Furthermore, a waterproof adhesive layer 76 is seen attaching the elements 72 and 74 to the abutting surfaces of the member 10. This arrangement has proved to provide a substantially permanent attachment of the felt elements; and a highly servicable bushing for a front rail or balance rail pin results.

The manner in which the present invention may be practiced, its method aspects and the purposes to which it may be put are believed evident from the foregoing descriptions.

The specific examples herein shown and described should be considered as illustrative only. Various changes may occur to those skilled in the art; and these changes are to be understood as forming a part of this invention insofar as they fall within the true spirit and scope of the appended claims.

The invention is claimed as follows:

1. The method of applying resilient material to opposite sidewall portions of a slot fashioned in a member defining a key lever for a musical instrument, said method comprising the steps of: supplying separate lengths of a resilient friction material with respective surface portions thereof disposed in confronting relationship; coating adhesive material on opposite surface portions of the respective lengths of material; continuously advancing a plug element in a path between the uncoated, confronting surface portions of said lengths and toward a said slot; pressurably contacting said moving plug element with the uncoated, confronting surface portions of said lengths to assemble said plug element and said lengths; inserting said plug element and the portions of adhesively coated friction material sandwiching said plug element into said slot; stopping the motion of said plug element; and withdrawing said plug element after the adhesive material has set.

2. The method according to claim 1 wherein said lengths of resilient friction material are substantially continuous lengths.

3. The method according to claim 1 which comprises the additional step of severing said friction material adjacent said plug element after the motion of said plug element has been stopped.

5 6 4. The method according to claim 1 wherein said mem- References Cited by the Examiner her is fashioned with a plurality of slots and wherein said UNITED STATES PATENTS method comprises the additional step of repeating the 3 184 362 5/1965 Litsky et aL X steps recited in claim 1 for a second one of said slots.

5. The method according to claim 1 wherein said ad- 5 EARL BERGERT, Examine"- hesive material is waterproof. HAROLD ANSHER, Examiner. 

1. THE METHOD OF APPLYING RESILIENT MATERIAL TO OPPOSITE SIDEWALL PORTIONS OF A SLOT FASHIONED IN A MEMBER DEFINING A KEY LEVER FOR A MUSICAL INSTRUMENT, SAID METHOD COMPRISING THE STEPS OF: SUPPLYING SEPARATE LENGTHS OF A RESILIENT FRICTION MATERIAL WITH RESPECTIVE SURFACE PORTIONS THEREOF DISPOSED IN CONFRONTING RELATIONSHIP; COATING ADHESIVE MATERIAL ON OPPOSITE SURFACE PORTIONS OF THE RESPECTIVE LENGTHS OF MATERIAL; CONTINUOUSLY ADVANCING A PLUG ELEMENT IN A PATH BETWEEN THE UNCOATED, CONFRONTING SURFACE PORTIONS OF SAID LENGTHS AND TOWARD A SAID SLOT; PRESSURABLY CONTACTING SAID MOVING PLUG ELEMENT WITH THE UNCOATED, CONFRONTING SURFACE PORTIONS OF SAID LENGTHS TO ASSEMBLE SAID PLUG ELEMENT AND SAID LENGTHS; INSERTING 